I know nothing about that brand or even dirt bikes, I've got a 28" road bike but I can tell you just by looking they are lying through their teeth with those numbers.   You aren't getting 45 mph unless you're pedaling like made down a steep hill with a 50 mph wind at your back.   

Same with the 40 mile range.  If you want 40 miles out the battery you'll have to set the pedal assistance on "1" and pedal hard.   Even then I doubt it.